Dot matrix-based single-box three-chamber box girder hydration temperature gradient design method and system

Abstract

The present disclosure provides a dot matrix-based single-box three-chamber box girder hydration temperature gradient design method and system. The experimental measuring point arrangement of the hydration heat temperature field of the method is sufficient, which can comprehensively reflect the most unfavorable temperature distribution of the structure, and can calculate the temperature gradient value at different times and different positions. The vertical temperature gradient of the side web plate and the middle web plate of the box girder is fitted by y=a(t)x 2 +b(t)x+c(t), and a three-fold line model is used for the obtained vertical temperature gradient time curve, so as to obtain the vertical temperature gradient at any position at any time in the hydration heat stage. For the transverse temperature gradient of the top plate, the distribution curve is also fitted by y=a(t)x 2 +b(t)x+c(t), a two-fold line model is used for the obtained transverse temperature gradient time curve, so as to obtain the transverse temperature gradient at any position at any time in the hydration heat stage, which is beneficial to accurately calculating the temperature gradient value of the box girder, and provides a reference for subsequent temperature distribution evaluation of the same type of bridge section and bridge crack resistance.

Description

Technical Field

[0001] This disclosure relates to the field of concrete hydration heat design technology, specifically to a hydration temperature gradient design method for single-box three-chamber box girders based on a lattice structure. Background Technology

[0002] The statements in this section are merely background information relating to this disclosure and do not necessarily constitute prior art.

[0003] The mixing of cement and water generates a significant amount of heat. Due to rapid heat exchange on the concrete surface, a large temperature difference forms between the inside and outside of the concrete. Different parts of the bridge structure are at different temperature states, leading to varying degrees of temperature deformation. This uneven deformation results in substantial temperature stress in the concrete, making it prone to cracking due to the heat of hydration in the early stages of concrete pouring. Current research on the heat of hydration primarily focuses on bridge piers and bridge decks.

[0004] However, the structure and thermal boundary conditions of a single-box multi-cell box girder section differ from those of bridge piers and bridge decks. The top, bottom, and web plates of the box girder have different hydration heat distribution characteristics. Current technologies mainly study the hydration heat distribution of box girder sections by combining measured data from characteristic points with numerical simulations. However, the box girder section is hollow and has complex boundaries, with many factors affecting hydration heat distribution. Even if the finite element model is modified using concrete thermal parameters, it is still difficult to accurately predict the temperature development law of this type of structure. Based solely on measured data from characteristic points along the depth or height direction, the selection of measurement points depends on experience and cannot fully reflect the most unfavorable temperature distribution of the structure. There is still no effective solution for studying the lattice-type temperature field of a single-box three-cell beam section. Summary of the Invention

[0005] To address the aforementioned problems, this disclosure proposes a hydration temperature gradient design method for single-box three-cell box girders based on a lattice design. This method fully considers the different hydration heat distribution characteristics of the top slab, bottom slab, and web, thereby enabling the calculation of temperature gradient values ​​at different times and locations.

[0006] According to some embodiments, the present disclosure adopts the following technical solutions:

[0007] A lattice-based design method for the hydration temperature gradient of a single-box three-chamber box girder includes:

[0008] Real-time temperature data of the concrete box girder section of the model and meteorological data of the surrounding environment were collected.

[0009] Based on the real-time temperature data of the concrete box girder section and the meteorological data of the surrounding environment, a two-dimensional temperature distribution cloud map of the concrete box girder section at different times of time and a scatter plot of solar radiation and wind speed with maximum temperature difference were drawn.

[0010] Based on the temperature distribution cloud maps at different times, the distribution law of temperature change with time at any position of the box girder section is obtained, and several characteristic position points are selected to analyze the temperature change at the characteristic position points to obtain the hydration temperature time history curve; based on the scatter plot, the influence of hydration heat, solar radiation and wind speed on the concrete temperature gradient is analyzed.

[0011] Based on the hydrothermal temperature distribution cloud maps of characteristic points at different times, the vertical and horizontal temperature gradients at different times are calculated, and the time history formulas for the vertical and horizontal temperature gradients are fitted.

[0012] According to other embodiments, the present disclosure adopts the following technical solutions:

[0013] Multiple sensors are used to collect real-time temperature data of the concrete box girder section of the model and meteorological data of the surrounding environment;

[0014] The data processing center is used to draw two-dimensional temperature distribution cloud maps of the concrete box girder cross section at different times over time, as well as scatter plots of solar radiation and wind speed with maximum temperature difference, based on the real-time temperature data of the acquired concrete box girder cross section and the meteorological data of the surrounding environment.

[0015] Based on the temperature distribution cloud maps at different times, the distribution law of temperature change with time at any position of the box girder section is obtained, and several characteristic position points are selected to analyze the temperature change at the characteristic position points to obtain the hydration temperature time history curve; based on the scatter plot, the influence of hydration heat, solar radiation and wind speed on the concrete temperature gradient is analyzed.

[0016] The data computing center is used to calculate the vertical and horizontal temperature gradients at different times based on the hydrothermal temperature distribution cloud maps of characteristic points at different times, and to fit the time history formulas for the vertical and horizontal temperature gradients.

[0017] Compared with the prior art, the beneficial effects of this disclosure are as follows:

[0018] This disclosure proposes a lattice-based design method for the hydration temperature gradient of a single-box three-cell box girder. This method features a comprehensive arrangement of experimental measurement points for the hydration heat and temperature field, effectively reflecting the most unfavorable temperature distribution of the structure and calculating temperature gradient values ​​at different times and locations. This disclosure facilitates accurate calculation of the box girder temperature gradient and provides a reference for subsequent assessment of temperature distribution in similar bridge sections and for evaluating bridge crack resistance. Attached Figure Description

[0019] The accompanying drawings, which form part of this disclosure, are used to provide a further understanding of this disclosure. The illustrative embodiments of this disclosure and their descriptions are used to explain this disclosure and do not constitute an undue limitation of this disclosure.

[0020] Figure 1This is a schematic diagram of the box girder dimensions; (unit: cm)

[0021] Figure 2 A schematic diagram showing the temperature measurement points layer by layer along the plate thickness; (unit: cm)

[0022] Figure 3 The measured temperature field during the hydration heat stage of the box girder;

[0023] Figure 4 This is a coordinate diagram of the temperature sensor dot matrix.

[0024] Figure 5 This is a typical distribution map of measuring points;

[0025] Figure 6 The hydration heat temperature time history curves are typical of the locations;

[0026] Figure 7 Temperature rise time history curves for each region;

[0027] Figure 8 A scatter plot of wind speed and solar radiation versus maximum temperature difference;

[0028] Figure 9 Vertical temperature distribution of each plate; (a) left web (b) right web (c) left middle web (d) right middle web

[0029] Figure 10 Number the web measuring points;

[0030] Figure 11 This represents the entire process of vertical temperature gradient change; (a) left web (b) left middle web

[0031] Figure 12 The time history curves show the vertical temperature gradient; (a) side web (b) middle web

[0032] Figure 13 The following is a comparison of theoretical and measured values ​​for vertical temperature gradient: (a) measured value of side web; (b) theoretical value of side web; (c) measured value of middle web; (d) theoretical value of middle web.

[0033] Figure 14 The horizontal temperature distribution of the top plate;

[0034] Figure 15 The curve shows the lateral temperature gradient distribution of the heat of hydration.

[0035] Figure 16 This is the time history curve of the transverse temperature gradient;

[0036] Figure 17 The diagram shows a comparison between theoretical and measured values ​​of the transverse temperature gradient; (a) measured value of the top plate and (b) theoretical value of the top plate. Detailed implementation method:

[0037] The present disclosure will be further described below with reference to the accompanying drawings and embodiments.

[0038] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0039] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this disclosure. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0040] Example 1

[0041] This disclosure provides, in one embodiment, a method for designing the hydration temperature gradient of a single-box three-chamber box girder based on a lattice-type structure, including:

[0042] Step 1: Collect real-time temperature data of the concrete box girder section of the model and meteorological data of the surrounding environment;

[0043] Step 2: Based on the real-time temperature data of the concrete box girder section and the meteorological data of the surrounding environment, draw a two-dimensional temperature distribution cloud map of the concrete box girder section at different times of time, as well as a scatter plot of solar radiation and wind speed with the maximum temperature difference.

[0044] Step 3: Based on the temperature distribution cloud map at different times, obtain the distribution law of temperature change with time at any position of the box girder section, and select several characteristic position points to analyze the temperature change at the characteristic position points to obtain the hydration temperature time history curve; based on the scatter plot, analyze the influence of hydration heat, solar radiation and wind speed on the concrete temperature gradient.

[0045] Step 4: Based on the hydrothermal temperature distribution cloud map of the feature points at different times, calculate the vertical and horizontal temperature gradients at different times, and fit the time history formulas for the vertical and horizontal temperature gradients.

[0046] Specifically, in step 1, before the beam is poured, the formwork is fabricated and the reinforcing steel frame is tied according to the scale of the reduced-size model. Figure 1To create the box girder dimension drawing, 258 temperature sensors need to be tied to the reinforcing steel frame with wire. Wind speed, wind direction, and solar radiation sensors should be installed at the top and bottom of the box girder to measure meteorological data of the surrounding environment. Sensors should also be installed within the reinforcing steel frame for wireless data acquisition after pouring. The testing method involves continuous data acquisition at a fixed frequency within a set time period, with a data acquisition frequency of 30 minutes / time, and a set time of no less than 96 hours. Based on the data collected 96 hours after pouring, various curves illustrating the changing patterns should be plotted.

[0047] The aforementioned method involves installing wind speed, wind direction, and solar radiation sensors at the top and bottom of the box girder to measure meteorological data of the surrounding environment. Furthermore, a temperature section is placed in the center of the model, with a total of 258 temperature sensors embedded within it. Figure 2 As shown, in order to accurately reflect the temperature gradient, the sensor measuring points are arranged relatively densely at the axles of the top and bottom plates. The sensor positions need to be adjusted according to the reinforcement positions, and the sensor measuring point positions are corrected one by one before concrete pouring.

[0048] Based on real-time temperature data collected by sensors, a two-dimensional temperature distribution cloud map of the concrete box girder cross-section over time is plotted, such as... Figure 3 As shown;

[0049] like Figure 4 As shown, a local coordinate system is established on the cross section of the concrete box girder to be measured, the coordinates of each temperature measuring point are determined, and a point matrix coordinate index for the temperature sensor is established. Specifically, the coordinate index is established by describing and storing each coordinate point based on the determined coordinates of each temperature measuring point, which facilitates the location of different measuring points.

[0050] Based on the temperature distribution cloud map at different times, the distribution law of temperature change with time at any position of the box girder section is obtained, and several characteristic position points are selected to analyze the temperature change at the characteristic position points to obtain the time history curve of hydration temperature; based on the scatter plot, the influence of hydration heat, solar radiation and wind speed on the temperature gradient of concrete is analyzed.

[0051] Specifically, such as Figure 5 as well as Figure 6 As shown, 12 feature points on the top plate, bottom plate and web of the box girder model were selected. Based on the measured values ​​of the hydration temperature of the box girder section in Table 1, the temperature changes in the top plate, bottom plate and web areas were analyzed to obtain the hydration temperature time history curves of typical locations.

[0052] Table 1 Measured values ​​of hydrothermal temperature of box girder cross section

[0053]

[0054] like Figure 7As shown, the average temperature of each part was calculated by averaging the 96-hour measured data from the top plate, bottom plate, web plate, and the entire cross-section of the box girder. Then, average the average temperatures to obtain the cross-sectional temperature Ta. Subtract the average temperature at entry into the mold from the average temperature at each time point to obtain the average temperature rise of each region. Plot the temperature rise time history curves for each region as follows: Figure 7 As shown.

[0055] like Figure 8 As shown, based on the scatter plot of solar radiation and wind speed versus maximum temperature difference, the effects of hydration heat, solar radiation, and wind speed on the temperature gradient of concrete can be analyzed. From the scatter plot, it can be seen that the temperature effect of hydration heat is much greater than the effect of solar radiation and wind speed, and the temperature gradient of concrete is not directly related to the effects of solar radiation and wind speed.

[0056] Based on the hydrothermal temperature distribution cloud map of the characteristic points at different times, the vertical and horizontal temperature gradients at different times are calculated. Specifically, the middle part of the bottom of each web is selected as the origin of the coordinate system, and the height of each measuring point is divided by the beam height for normalization.

[0057] Using the height of each measuring point as the x-axis, the time after pouring as the y-axis, and the measured temperature value as the z-axis, a cloud map of the hydration heat temperature distribution along the web height at different times is plotted. Figure 9 The vertical temperature distribution of each plate.

[0058] Furthermore, since the temperature distribution of the side webs on both the left and right sides is similar to that of the middle web, only the two webs on the left side are analyzed for hydration heat temperature rise. The vertical temperature gradient is obtained by subtracting the lowest vertical temperature from the temperature at each measuring point, and the curves of the vertical temperature gradient at each measuring point changing with time are plotted, as shown below. Figure 11 As shown.

[0059] Furthermore, the curve based on the vertical temperature gradient can be approximated by a quadratic function y = a(t)x. 2 The expression is described by +b(t)x+c(t).

[0060] Furthermore, based on the vertical temperature gradient time history curve, a three-segment model is established, thereby proposing the vertical temperature gradient time history formula for the side web and the middle web.

[0061] First, the side web plate is as follows:

[0062]

[0063]

[0064]

[0065] In the formula: t is the time after the box girder is poured (unit: h). The web is as follows:

[0066]

[0067]

[0068]

[0069] Furthermore, substituting a(t), b(t), and c(t) from the simplified model into:

[0070] y = a(t)x 2 +b(t)x+c(t) (7)

[0071] To obtain the vertical temperature gradient at any time and location during the heat of hydration stage, a three-dimensional cloud map of the theoretical and actual temperature gradients is plotted.

[0072] The midpoint of the left side of the top slab is selected as the origin of the coordinate system. The width of each measuring point is normalized by dividing the width by the beam width. Using the x-axis as the x-axis, the time after pouring as the y-axis, and the measured temperature value as the z-axis, plot the hydration heat temperature distribution cloud map along the width of the top slab at different times.

[0073] Furthermore, the lateral temperature gradient is obtained by subtracting the lowest lateral temperature from the temperature at each measuring point, and the distribution curve of the lateral temperature gradient at each key moment is plotted every 6 hours.

[0074] Furthermore, the transverse temperature gradient of hydration heat at each moment shows a peak at the junction of the top plate and the four web plates, also exhibiting a trend of being higher in the middle and lower at both ends, which can be approximated by the quadratic function y = a(t)x. 2 The data is described by +b(t)x+c(t). Due to the large number of measurement points, only the left half of the test data is plotted, showing the temperature gradient changes over time at some measurement points.

[0075] Furthermore, the trend of the vertical temperature gradient at each measuring point over time can be roughly simplified as follows: Figure 16 The red broken line represents the lateral temperature gradient at each measuring point, which peaks at 12:00 and then approaches zero after 96 hours. This can be simplified to a bilinear model.

[0076]

[0077]

[0078]

[0079] Substituting a(t), b(t), and c(t) from the simplified model into equation (7),

[0080] y = a(t)x 2 +b(t)x+c(t)

[0081] The vertical temperature gradient at any time and location during the heat of hydration can be obtained, and a three-dimensional cloud map of the theoretical and actual temperature gradients can be drawn.

[0082] Example 2

[0083] One embodiment of this disclosure provides a hydration temperature gradient design system for a single-box three-chamber box girder based on a lattice structure, comprising:

[0084] Multiple sensors are used to collect real-time temperature data of the concrete box girder section of the model and meteorological data of the surrounding environment;

[0085] The data processing center is used to draw two-dimensional temperature distribution cloud maps of the concrete box girder cross section at different times over time, as well as scatter plots of solar radiation and wind speed with maximum temperature difference, based on the real-time temperature data of the acquired concrete box girder cross section and the meteorological data of the surrounding environment.

[0086] Based on the temperature distribution cloud maps at different times, the distribution law of temperature change with time at any position of the box girder section is obtained, and several characteristic position points are selected to analyze the temperature change at the characteristic position points to obtain the hydration temperature time history curve; based on the scatter plot, the influence of hydration heat, solar radiation and wind speed on the concrete temperature gradient is analyzed.

[0087] The data computing center calculates the vertical and horizontal temperature gradients at different times based on the hydrothermal temperature distribution cloud maps of characteristic points at different times, and fits the time history formulas for the vertical and horizontal temperature gradients.

[0088] Those skilled in the art will understand that embodiments of this disclosure can be provided as methods, systems, or computer program products. Therefore, this disclosure can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this disclosure can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0089] This disclosure is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create a machine for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0090] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0091] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0092] The above description is merely a preferred embodiment of this disclosure and is not intended to limit this disclosure. Various modifications and variations can be made to this disclosure by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

[0093] While the specific embodiments of this disclosure have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of this disclosure. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of this disclosure are still within the scope of protection of this disclosure.

Claims

1. A hydration temperature gradient design method for single-box three-chamber box girders based on a lattice structure, characterized in that, include: Real-time temperature data of the concrete box girder section of the model and meteorological data of the surrounding environment were collected. Based on the real-time temperature data of the concrete box girder section and the meteorological data of the surrounding environment, a two-dimensional temperature distribution cloud map of the concrete box girder section at different times of time and a scatter plot of solar radiation and wind speed with maximum temperature difference were drawn. Based on the temperature distribution cloud maps at different times, the distribution law of temperature change with time at any position of the box girder section is obtained, and several characteristic position points are selected to analyze the temperature change at the characteristic position points to obtain the hydration temperature time history curve; based on the scatter plot, the influence of hydration heat, solar radiation and wind speed on the concrete temperature gradient is analyzed. Based on the hydrothermal temperature distribution cloud maps of characteristic points at different times, the vertical and horizontal temperature gradients at different times are calculated, and the time history formulas for the vertical and horizontal temperature gradients are fitted. Based on the vertical temperature gradient time history curve, a three-segment model is established, and the vertical temperature gradient time history formulas for the side web and the middle web are proposed. The time history formula for the side web is: where... t Time after box girder pouring (unit: h): ； Substitute a(t), b(t), and c(t) into the... The vertical temperature gradient at any time and location during the hydration heat stage is obtained, and a three-dimensional cloud map of the theoretical annual gradient and the actual temperature gradient is plotted.

2. The hydration temperature gradient design method for a single-box three-cell box girder based on a lattice structure as described in claim 1, characterized in that, Wind speed, wind direction, and solar radiation sensors are installed at the top and bottom of the box girder to measure meteorological data of the environment in which the box girder is located.

3. The hydration temperature gradient design method for a single-box three-chamber box girder based on a lattice structure as described in claim 1, characterized in that, A local coordinate system is established on the concrete box girder section to determine the coordinates of each temperature measuring point and to establish a point matrix coordinate index for the temperature sensor.

4. The hydration temperature gradient design method for a single-box three-chamber box girder based on a lattice structure as described in claim 1, characterized in that, Multiple characteristic points on the top plate, bottom plate, and web of the box girder are selected. Based on the measured values ​​of the hydration heat temperature of the box girder section, the temperature changes in the top plate, bottom plate, and web regions are analyzed to obtain the hydration heat temperature time history curves at the characteristic point locations.

5. The hydration temperature gradient design method for a single-box three-chamber box girder based on a lattice structure as described in claim 4, characterized in that, The average temperature of each part was calculated by taking the average of the measured data of the top plate, bottom plate, web plate and the overall temperature of the box girder section for 96 hours. The average temperature of each part was then calculated by taking the average of the average temperatures. The average temperature of each part was then subtracted from the average temperature of the mold at each time to obtain the average temperature rise of each region. The temperature rise time history curve of each region was then plotted.

6. The hydration temperature gradient design method for a single-box three-chamber box girder based on a lattice structure as described in claim 5, characterized in that, Hydration heat temperature rise analysis was performed on the two web plates on the left side. The vertical temperature gradient was obtained by subtracting the lowest vertical temperature from the temperature at each measuring point, and the curve of the vertical temperature gradient at each measuring point changing with time was plotted.

7. A lattice-based single-box three-chamber box girder hydration temperature gradient design system, specifically implementing the lattice-based single-box three-chamber box girder hydration temperature gradient design method as described in any one of claims 1-6, characterized in that, include: Multiple sensors are used to collect real-time temperature data of the concrete box girder section of the model and meteorological data of the surrounding environment; The data processing center is used to draw two-dimensional temperature distribution cloud maps of the concrete box girder cross section at different times over time, as well as scatter plots of solar radiation and wind speed with maximum temperature difference, based on the real-time temperature data of the acquired concrete box girder cross section and the meteorological data of the surrounding environment. Based on the temperature distribution cloud maps at different times, the distribution law of temperature change with time at any position of the box girder section is obtained, and several characteristic position points are selected to analyze the temperature change at the characteristic position points to obtain the hydration temperature time history curve; based on the scatter plot, the influence of hydration heat, solar radiation and wind speed on the concrete temperature gradient is analyzed. The data computing center is used to calculate the vertical and horizontal temperature gradients at different times based on the hydrothermal temperature distribution cloud maps of characteristic points at different times, and to fit the time history formulas for the vertical and horizontal temperature gradients.

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